Review: Desktop virtualization made easy

Ever since VMware coined the term, virtual desktop infrastructure (VDI) has conjured images of large data centers, beefy servers, centralized storage, and complex software stacks. It's a given that each VDI installation requires numerous servers, software packages, and storage systems in order to provide desktop virtualization for more than a small handful of users, so VDI just has to be both expensive and complicated to deploy. Right?

As I found out while evaluating three entry-level VDI bundles, this doesn't have to be the case. My goal was to find out just how much -- or how little -- was needed to provide a scalable virtualized desktop system for up to 50 users. As with just about all matters computer related, there are many ways to skin a virtualized cat, and some will fit into an existing network infrastructure better than others.

The VDI products I tested are Kaviza VDI-in-a-box, NComputing vSpace and L-Series endpoint devices, and Pano Logic's Pano Express. All three provide centrally hosted, general-purpose desktops to end-users for less than $500 per seat. With all three products, I was able to connect to Windows XP Pro or Windows 7 Pro desktops hosted on a single piece of hardware -- no network storage necessary. While all three solutions set up easily, worked well, and will meet the needs for about 80 percent of businesses, each one did have some shortcomings. IT organizations will have to carefully evaluate any potential solution to make sure it fits in with their use case.

In general, even the simplest VDI solution is made up of five components: a connection broker, a remote access protocol, a back-end virtualization platform, a storage system, and client devices. The VDI solutions reviewed here addressed these components a bit differently, and these variations will be key to choosing which among them is the best fit for your organization. Each solution overlaps another in some areas, but they all have a feature or two that make them unique.

The virtualization in VDI One key difference among the solutions is the choice of virtualization platform. Both Kaviza and Pano Logic sit on top of a bare-metal hypervisor, or Type 1 virtualization infrastructure, which hosts both the management component and the desktop virtual machines. Pano Logic includes the VMware or Microsoft virtualization infrastructure as part of the bundle, while Kaviza requires an existing virtualized infrastructure (either VMware or Citrix XenServer). NComputing, on the other hand, provides its own form of virtualization, called vSpace, which is more akin to Terminal Services than VMware, Hyper-V, or XenServer. NComputing's vSpace is an application that needs only a Windows XP Pro or Windows Server 2003 box to run on, allowing up to 30 concurrent users on basic, off-the-shelf hardware.

When choosing among Kaviza, NComputing, and Pano Logic, the question becomes one of virtual machines versus a shared operating system environment for the end-user desktops. With Kaviza and Pano Logic, you can create different virtual machine images for different user profiles. With NComputing, all users run the same OS and applications as the host. In return for the generic user environment, both hardware and administrative requirements are lower.

Like a lot of IT hot-button topics, some admins feel strongly about one flavor of virtualization versus another. During my tests, I had no problems with any of the VDI solutions. While I only scaled up to 10 concurrent users, all three performed well and none gave me any indication that I was in jeopardy of running out of resources. (For more on Terminal Services and thin client computing versus VDI, see InfoWorld's Thin Client Computing Deep Dive and VDI Deep Dive reports.)

Personalizing virtual desktops One of VDI's more interesting features is on-the-fly creation of clean virtual machines from standard images as users log on. By deploying nonpersistent desktop VMs, there is no chance of permanent damage from viruses, malware, or user error. To bring each user's personal settings to these dynamic desktop VMs (or to each user session, in the case of NComputing), the three solutions all take advantage of Active Directory roaming profiles.

Roaming profiles are one of the oldest ways to provide user personalization on Windows-based networks. Through Active Directory group policy, a user's personalization information is collected from the local profile and stored on a server somewhere in the domain. This stored profile includes the My Documents folder, Outlook email settings, printer assignments, desktop icons, and other settings that make the desktop environment unique to the user.

The roaming profile is part of the Windows user identity and independent of the underlying system. That means a roaming profile will provide the personal user settings to any Windows device in the domain: a physical desktop, virtual desktop, or Terminal Services user session. The profile is applied during the logon process, and any changes made during the session are saved on logout. Roaming profiles are not fancy, but they are very effective at giving the end-user the perception of a persistent desktop when in fact the virtual desktop is newly created upon each logon.

Making the virtual desktop connection The connection broker is another important component, especially when it comes to handling a VDI infrastructure with dozens of users. With respect to VDI, a connection broker is a service that handles incoming user requests and automatically directs them to an available host server.

Kaviza does a good job of handling user access to desktop VMs and load balancing among host servers as part of its management platform. NComputing doesn't really have the concept of connection brokering because each user that connects to a vSpace host will run a session of the same operating system as the host itself. Users can pick and choose among vSpace hosts, but it is not an automatic process. Pano Express, like Kaviza, does provide connection brokering. The Pano Express solution can work with third-party connection brokers, too, to provide load balancing.

A major differentiator is the remote access protocol and the endpoints each solution supports. Kaviza will allow any client, fat or thin, that can run Microsoft RDP (Remote Desktop Protocol) or Citrix HDX to connect to a guest VM. NComputing developed its own UXP protocol that works only with its proprietary endpoints. Finally, Pano Express uses a proprietary UDP-based protocol to extend the desktop VM's hardware bus to its proprietary endpoint device.

From a deployment standpoint, Kaviza isn't locked into a single endpoint and can work with a wide range of devices. Both NComputing and Pano Logic are locked into using their specific endpoint hardware, eliminating Web-based access. There are advantages to using NComputing's and Pano Logic's client devices -- they draw very little power; have no CPU, RAM, or local storage; and fit in the palm of your hand. There is no chance of anyone walking away with business secrets if a device is stolen, and if a device fails, you simply plug in a new one. They are an excellent way to provide everyday access for moderate line-of-business use.

With all three solutions, virtual desktop OS support is limited to 32-bit Windows. All three will work with Windows XP Pro, and Kaviza and Pano Logic also work with Windows 7 Pro. NComputing's vSpace will run on Windows Server 2003 R2, with support for Windows Server 2008, Windows Vista, and Windows 7 coming in future releases. Look for 64-bit Windows support to be addressed by all three vendors in future releases.

The result of my testing is that VDI on the cheap is here and quite capable of fitting into the enterprise regardless of your stage of virtualization. I very much like Pano Logic's complete bundle concept, and NComputing's vSpace virtualization software is a real technological achievement. I am not overly fond of being locked into proprietary endpoints with both NComputing and Pano Logic, but I have to admit that in all my testing, the endpoints worked very well and performed all basic office tasks without a complaint.

Overall, the Kaviza solution best combines flexibility, scalability, and virtual desktop management into a single package. I like that I am not tied to any particular endpoint, and Kaviza's VM image management is well done. My biggest knock on Kaviza is that it takes a bit of work to get your guest VMs in the system and prepped for deployment to the end-users. For an at-a-glance comparison of the three solutions, see the table below. For full details, please read the individual reviews:

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